Friction-drive.



R. SHIPMAN.

FRICTION DRIVE.

APPLICATION FILED FEB. 5. 1913. RENEWED JUNE 29.19I6.

1,235,940. PatentedAug. 7,1917. 1 291;.

' INVENTOR WITNESSES MAT/W RALPH SHIPMAN, OF SUNBURY, PENNSYLVANIA.

FRICTION-DRIVE.

Specification of Letters Patent.

Application filed February 5, 1913, Serial No. 746,344. Renewed June 29,1916.

To all whom it may concern:

Be it known that I, RALPH SHIPMAN, a

.citizen of the lhiited States, residing at Sunbury, inthe county ofNorthumberland and State of Pennsylvania, have invented certain new anduseful Improvements in Friction-Drives, of which the following is aspecification.

The purpose of this invention is to provide a self contained. frictiondrive which can be readilyapplied to mechanisms of various kinds,between the source of power "and the mechanism to be driven, and whichwill maintain the torque of the driven mechanism constant, where theIGSISMLHCB Of the load "is constant, notwlthstanding variations inthespeed of the driving means.

In the accompanying drawing,

Figure 1 is a viewpartly in central section and'partly in sideelevation, showing one form of friction drive applied to the windingshaft of a moving," picture machine;

Fig. 2 is a section on thehne 2 -2 of Fig. l;

Fig. 3 isa central sectional view through a n1odified form'of frictiondrive;

Fig. 4 is a section on the Fig.3; and,

Fig. 5 .is a

line H of side elevation-of a friction -;...i ..drive' similar to thatshojwiiin Fig. 1, Hipstrating its application to a clock train operatedby a flexible shaft.

Referring to igs. 1 and 2 of the drawing, wherein the friction drive isshown, for the purpose of illustration, upon the winding shaft of amoving picture machine, 1 indicates a driving pulley, loosely mountedupon a shaft 2 which carries the filin-winding reel 3. Upon this shaftis also secured. a disk i, and between said disk and the driving pulleyis arranged the friction drive mechanism, indicated. as a whole uresreferred to, comprises a sleeve 5 which fits loosely on the shaft 2 andis provided with a driving head or'mcmber 6, and an external worm orthreaded portion 7 adjacent the head. The head is provided with a.lateral flange G forming a'housing, Within which is arranged a flatspiral spring 8 having one oronore coils wound about the axis of thesleevesaid spring having one owl-connected to said flange and. the otherend connected to the hub 9 of a friction disk 9 which is internallythreaded, and

head 6 will be carried '1 and pintle 12, in the direction indicatedAnother iction disk 10 is journaled upon a smooth bearlng portion 5 ofthe sleeve.

The spiral spring 8 constantly tends to turn thefriction disk 9 on thethreads of the sleeve in the direction to carry said disk away from thehead 6 and against the friction disk 10. The latter is held againstongitudinal movement on the sleeve by a collar 11, secured to thesleeve, and located so as to position the disk 10 with respect to thedisk 9 so as to give the desired degree of friction between the evidentthat the amount of friction between the disks may be varied by slightlychanging the position of the collar 11. When the sleeve 5 and the partsmounted thereon, constituting the friction drive, are to be appliedbetween the power source and the load to be driven, the sleeve is placedon the shaft.

as shown, and the driving member or head 6 is connected to the drivingsource, while the friction disklO is connected to the load tobe driven.Thus, in Fig. l, the driving head 6 is provided with a pintle 12 whichenters a perforation in the. web of the pulley 1, so that when thepulley is driven, the driving head will be carried around positivelythereby, and the disk l0 is provided with a pintle 13 which enters asuitable perforation in the disk 4 so that when. the disk 10 turns, itwill drive the disk 4 and the shaft 2. In operation, when the pulley lof Fig. l is driven by a belt, the sleeve 5 and driving around by thepulley by the arrow, Fig. 2, and the friction disk 9 will be draggedaround by thespiral spring 8. The friction disk 10 will also be drivenby reason of its engagement with the disk 5). and the disk 4, shaft 2,and reel 3 will turn in unison with the friction disk 10. It isdesirable, in a moving picture machine, to have the take-up 'rcol exerta uniform pull noon the film while the pictu es are being exhibited, butsuch machines are very commonly operated byhand and it is dii'licult fortheoperator to operate the reel so as to maintain this uniform tractiveeffort upon the film, notwithstanding provision is made for allowing thedriving belt to slip when the power applied thereto increases above acertain amount. As the load or resistance is ncarlv constant, it will beseen that with the friction drive of my in-v vention, if the speed ofthe driving pulley disks. It Will be 1, and hence of the driving head(i, is increased, the slightly greater friction occurring between thedisks 9 and 10 will cause the disk S) to turn on the worm 7, against theaction of the spring 8, in the direction which will lessen thefrictional engagement of the disks 9 and 10. As thespring constantlyurges the disk 9 toward the disk 10, it will be evident that the twodisks will he always held in engagement, but that ther will he more orless slippage between them, according to the fluctuations in the speedof the driving pulley, and hence the driven shaft and the reel thereonwill be driven with a practically constant torque, regardless offluctuations in speed of the driving means.

In Fig. 5, the friction drive A is substantially the same as that shownin Fig. 1, the difference being that gears 14: and 15 are substitutedfor the pins 12 and 13. In Fig. 5, the friction drive is showninterposed between a flexible shaft 16, and a gear 17 which may be themain driving gear of a clock train in certain types of instruments usedfor indicating the running time and speed of motor cars, or othervehicles, where the clock train is actuated by the movement of thevehicle through the medium of a flexible shaft. As the clock trainoffers a constant resistance, while the speedof the flexible shaftvaries, it will be seen that the friction drive will cause a constantforce to be applied to the clock train, notwithstanding widefluctuations in the speed of the flexible shaft. In applying thefriction drive to a clock mechanism, it is merely necessar to slip .thesleeve 5, on to a spindle 1 8, suita ly arranged between supportingplates 19 and 20 of the clock mechanism.

In the friction drive A, shown in Figs. 8 and Hi, the parts are mountedupon a tubular shaft or sleeve 21 which is to be secured, as by means ofa set screw 22, to the shaft 2 of a moving picture machine or othermechanism. Upon this tubular shaft or sleeve 21 is mounted a sleeve 5having external threads 7, and a head 6* is secured to the sleeve, andthis sleeve has a lateral flange 6, within which is arranged a flatspiral sprin 8 having one and secured to said flange, an its oppositeend secured to the hub 9" of a. friction disk 9. This friction diskengages a friction disk 10? which is mounted upon the tubular shaft orsleeve 21, and connected to said sleeve by the set screw 22. The partsare held in their proper positions by a shoulder 21 on the tubularshaft, and an adjustable collar 23 on said shaft. Preferably, where thedevice is large and used for heavy work, a ring or washer 24 is placedbetween the friction disks 9 and 10, and this washer has tongues 24;which tend slightly to force the disks a art, this being merely toprevent the disks rom sticking together. In these figures also, I haveshown teeth 25 upon the driving member 6", adapted to be engaged by asuitable pawl 26, which pawl may be connected to a sprocket Wheel 28upon the shaft 2, by a suitable stud 27, where a sprocket chain drive isused instead of the pulley drive, as shown in Fig. 1.

In the operation of the device sl Figs. 3 and 4:, when the driving headu 18 turned, the friction disk 9 is dragged around with it by means ofthe spring, and through the engagement ofthe friction disks, thetubular-shaft 21, which supports the parts is driven along with theshaft 2. It will be evident that any increase in the speed of thedriving head, if the load to be driven is constant, will result inlessening the frictional contaetbetween the disks 9 and 10, and thespeed of the driven shaft will remain practically constant.

What I claim is:

1. In a friction drive mechanism a sleeve and a driving head or memberattached thereto, two co-engaging clutch-members, one loosely threadedon to said sleeve, and a spring wound about the axis of the sleeveconnecting said latter clutch-member witlr the driving member.

2. In a friction drive mechanism a sleeve and a driving head or memberattached thereto, said member having a lateral flange, two co-engagingclutch-members, one loosely threaded on to said sleeve, said lattermember having a hub, and a spiral spring connecting said flange withsaid hub.

3. In av friction drive mechanism a shaft to be driven, a sleevejournaled on said shaft and a driving head or member connected to thesleeve, said sleeve having an externally threaded portion, twoco-engaging clutchmembers, one loosely threaded onto the sleeve and theother connected to the shaft so as to drive the latter, and a spiralspring wound about the axis of the sleeve and connecting the firstmentioned clutch-member with the driving head.

4. A sleeve having a driving headthereon, said sleeve having an externalthread adjacent the head, two co-engaging friction disks journaled onthe sleeve, one engaging the thread, and a spiral spring connecting thelatter disk with the head.

5. A sleeve having a driving head thereon, said sleeve having anexternal thread adjacent the head, two co-engaging friction disksjournaled on the sleeve, one engaging the thread, a spiral springconnecting the latter disk with the head, and an adjustable stop on thesleeve for adjusting the position of the other disk.

6. A sleeve having a driving .head provided with a lateral flangeencircling the sleeve, said sleeve having an external thread adpicentthe head, two co-engaging frlction disks journaled on the sleeve, oneengaging the thread and having hub entending within said flange, and asplral spring connecting said flange With seidh'ub. 7. in a frictiondrive mechanism, a tn- :buier shaft, a sleeve mounted thereen, saidbnlarshaft, a sleeve meunted thereon, said sleeve having an external thread,a driving head attached to said sleeve, a clutch-meniher having threadsengaging the threads" on the sleeve, a spiral spring connecting saidclutch member With the head, a second c1ntch-member seemed to said shaftand engaging said first mentioned clutch member,

and a; spring between said clutch-members tending to press them apart.

9. A friction drive mechanism eornprising coaxial driving and drivenmembers, an ex} ternally threaded sleeve connected with one ofsaid-members, two engaging clutch-elements, one threaded onto the sleeveand the other eennected to the other of said members, ,and a springWound about the axis of .the said driving vand driven members andconneted t0 the threaded clutch element and to the adjacent driving ordriven -memher, the spring ancl'threads being relatively arranged tomaintain a constant frictional. 35

engagement between the clutch elements.

In testimony whereof I have afixed my signature, in presefiee 025 twoWitnesses. RALPH SHIPMAN.

Witnesses: i v J 012m HEISER Bassnnn,

. B. F. HECKERT.

